I haven't seen any IT company that would fix the salary based on SCWCD certification. When you have a technical certification it is just a signal to the prospective employer that you have the necessary skill for the given role. It does not also mean that those without an SCWCD are less skilled for the role. So the point here is, I do not see any monetary advantage an SCWCD certified candidate has.

SCJP 1.4, SCWCD 1.4 - Hints for you, Certified Scrum Master
Did a rm -R / to find out that I lost my entire Linux installation!

Salary depends on your experience, how well you perform in your job interviews, how many offers you get to be able to negotiate, networking, the type of company (e.g investment bank), role and responsibilities, etc and not on certification.